Biomedical subjects

J J Drake

Publications and source records attributed to J J Drake.

12 recordsLinked to original sources

PubMed1994

Detection of rotational modulation in the coronal extreme-ultraviolet emission from V711 Tauri?

The RS CVn binary V711 Tauri was observed by the Extreme Ultraviolet Explorer satellite (EUVE) twice during the latter half of 1992, for periods lasting several days. Light curves for the waveband 60-180 angstroms derived from the all-sky survey scanning in August and from a pointed calibration observation made in October both exhibit a modulation of about 40%. The modulation in both data sets is very similar, with minimum flux occurring near orbital phase phi=0.5. Analysis using a two-temperature optically thin plasma emission model reveals that most of the detected extreme ultraviolet (EUV) flux emanates from hot (approximately 10(7) K) coronal plasma. The modulation is probably mostly due to either flare-like activity or to rotational occultation of a long-lived, compact, and especially bright coronal structure on the more active star of the system. The phased data support the latter hypothesis. This coronal structure is then likely to be associated with the persistent spot patterns seen on V711 Tau when using Doppler and photometric surface imaging techniques. Comparison with contemporaneous Stromgren b-band photometry indicates that the optical minimum light leads the EUV maximum light by 90 degrees in phase.

Astronomy↗

PubMed1994

The geographic variation of cancer incidence in Ontario.

OBJECTIVES: Our objectives were (1) to describe an analysis of the spatial pattern of cancer incidence in Ontario and (2) to discuss the quality of data in the Ontario Cancer Registry with respect to the accuracy of local cancer rates. METHODS: Cancer incidence rates were calculated for 22 cancer sites in 49 counties of Ontario during 1976 to 1986. Capture-recapture methods were used to estimate completeness of case registration, and completeness of residence information was also assessed. Spatial autocorrelation was used in measuring the geographic pattern of incidence rates. Comparisons were also made between sexes and with earlier data from 1966 to 1975. RESULTS: The quality of the geographic data in the registry appeared good, and corrections for incomplete or inaccurate registration had little impact. About one third of the sex-site combinations showed some evidence of spatial patterning in the cancer rate. Particularly strong regional variation was noted for cancers of the stomach, lung, uterus, and prostate. CONCLUSIONS: The analysis revealed a number of cancers with significant spatial patterning of risk. Further work is needed to relate the cancer data to other information on potential life-style and environmental factors.

Female↗

PubMed1982

Long-term toxicity study quillaia extract in rats.

Groups of 48 male and 48 female rats were fed quillaia extract in the diet at levels of 0 (controls), 0.3, 1.0 and 3.0% for 2 yr. The material had no adverse effects on death rate, water consumption, serum chemistry or haematological parameters or on the incidence of histopathological findings, including tumours. In the males given the 3% dietary level, the death rate, total leucocyte count at wk 108, incidence of kidney lesions and weights of the kidneys, heart and thyroid were all below the control values. These differences were explicable, however, in terms of a lowered body weight consequent on a decreased food intake. It is concluded that, in rats, quillaia extract fed at levels up to 3.0% in the diet did not have any carcinogenic effect. The no-untoward-effect level established in this was 3.0% in the diet, approximately equivalent to an intake of 1.5 g/kg/day.

Animals↗

PubMed1978

Long-term toxicity studies of chocolate brown HT in mice.

Groups of 48 male and 48 female mice were given diets containing 0 (control), 0.01, 0.1 or 0.5% Chocolate Brown HT for 80 weeks. There was a slightly reduced body weight gain and a lower heart weight in males given the highest dietary level. At the same level at week 77 the packed cell volume and total leucocyte count values in females were lower than those of the controls. However, the relationship of these findings to the treatment was questionable, as was the increased incidence of leucocytic infiltration of the liver in the female mice at the 0.5% level of treatment. A brown coloration of internal organs seen at the highest treatment level was due probably to the Chocolate Brown HT. The distribution of tumours was similar in all groups and it was concluded that there was no evidence of a carcinogenic effect with doses up to 700 mg/kg/day while the no-untoward-effect level was greater than 140 mg/kg/day.

Animals↗

PubMed1978